Summary Cancer immune surveillance is considered to be an important host protection process to inhibit carcinogenesis and to maintain cellular homeostasis. In the interaction of host and tumour cells, three essential phases have been proposed: elimination, equilibrium and escape, which are designated the ‘three E’s'. Several immune effector cells and secreted cytokines play a critical role in pursuing each process. Nascent transformed cells can initially be eliminated by an innate immune response such as by natural killer cells. During tumour progression, even though an adaptive immune response can be provoked by antigen‐specific T cells, immune selection produces tumour cell variants that lose major histocompatibility complex class I and II antigens and decreases amounts of tumour antigens in the equilibrium phase. Furthermore, tumour‐derived soluble factors facilitate the escape from immune attack, allowing progression and metastasis. In this review, the central roles of effector cells and cytokines in tumour immunity, and the escape mechanisms of tumour cells during tumour progression are discussed.

Unfolded protein response (UPR) is an important genomic response to endoplasmic reticulum (ER) stress. The ER chaperones, GRP78 and Gadd153, play critical roles in cell survival or cell death as part of the UPR, which is regulated by three signaling pathways: PERK/ATF4, IRE1/XBP1 and ATF6. During the UPR, accumulated unfolded protein is either correctly refolded, or unsuccessfully refolded and degraded by the ubiquitin-proteasome pathway. When the unfolded protein exceeds a threshold, damaged cells are committed to cell death, which is mediated by ATF4 and ATF6, as well as activation of the JNK/AP-1/Gadd153-signaling pathway. Gadd153 suppresses activation of Bcl-2 and NF-kappaB. UPR-mediated cell survival or cell death is regulated by the balance of GRP78 and Gadd153 expression, which is coregulated by NF-kappaB in accordance with the magnitude of ER stress. Less susceptibility to cell death upon activation of the UPR may contribute to tumor progression and drug resistance of solid tumors.

Tumors evolve mechanisms to escape immune control by a process called immune editing, which provides a selective pressure in the tumor microenvironment that could lead to malignant progression. A variety of tumor-derived factors contribute to the emergence of complex local and regional immunosuppressive networks, including vascular endothelial growth factor, interleukin-10, transforming growth factor-B, prostaglandin E 2 , and soluble phosphatidylserine, soluble Fas, soluble Fas ligand, and soluble MHC class I-related chain A proteins. Although deposited at the primary tumor site, these secreted factors could extend immunosuppressive effects into the local lymph nodes and the spleen, promoting invasion and metastasis. Vascular endothelial growth factors play a key role in recruiting immature myeloid cells from the bone marrow to enrich the microenvironment as tumor-associated immature dendritic cells and tumor-associated macrophages. The understanding of the immunosuppressive networks that evolve is incomplete, but several features are emerging. Accumulation of tumor-associated immature dendritic cells may cause roving dendritic cells and T cells to become suppressed by the activation of indoleamine 2,3-dioxygenase and arginase I by tumor-derived growth factors. Soluble phosphatidylserines support tumor-associated macrophages by stimulating the release of anti-inflammatory mediators that block antitumor immune responses. Soluble Fas, soluble FasL, and soluble MHC class I-related chain A proteins may help tumor cells escape cytolysis by cytotoxic T cells and natural killer cells, possibly by counterattacking immune cells and causing their death. In summary, tumor-derived factors drive the evolution of an immunosuppressive network which ultimately extends immune evasion from the primary tumor site to peripheral sites in patients with cancer. (Cancer Res 2006; 66(11): 5527-36)

Mitochondria play a crucial role in regulating cell death, which is mediated by outer membrane permeabilization in response to death triggers such as DNA damage and growth factor deprivation. Mitochondrial membrane permeabilization induces the release of cytochrome c, Smac/DIABLO, and AIF, which are regulated by proapoptotic and antiapoptotic proteins such as Bax/Bak and Bcl-2/xL in caspase-dependent and caspase-independent apoptosis pathways. Mitochondrial dysfunction is mediated in two ways. The first is by increased calcium in mitochondria derived from endoplasmic reticulum (ER); this calcium increase is regulated by Bcl-2 and Bax through the ER-mitochondria connection and the unfolded protein response in the ER. The second is by the lysosomal enzyme cathepsin, which activates Bid through lysosome-mitochondria cross-signaling. The genomic responses in intracellular organelles after DNA damage are controlled and amplified in the cross-signaling via mitochondria; such signals induce apoptosis, autophagy, and other cell death pathways. This review discusses the recent advancements in understanding the molecular mechanism of mitochondria-mediated cell death.

Summary Cancer immunosuppression evolves by constitution of an immunosuppressive network extending from a primary tumour site to secondary lymphoid organs and peripheral vessels and is mediated by several tumour‐derived soluble factors (TDSFs) such as interleukin‐10 (IL‐10), transforming growth factor‐β (TGF‐β) and vascular endothelial growth factor (VEGF). TDSFs induce immature myeloid cells and regulatory T cells in accordance with tumour progression, resulting in the inhibition of dendritic cell maturation and T‐cell activation in a tumour‐specific immune response. Tumour cells grow by exploiting a pro‐inflammatory situation in the tumour microenvironment, whereas immune cells are regulated by TDSFs during anti‐inflammatory situations—mediated by impaired clearance of apoptotic cells—that cause the release of IL‐10, TGF‐β, and prostaglandin E2 (PGE2) by macrophages. Accumulation of impaired apoptotic cells induces anti‐DNA antibodies directed against self antigens, which resembles a pseudo‐autoimmune status. Systemic lupus erythematosus is a prototype of autoimmune disease that is characterized by defective tolerance of self antigens, the presence of anti‐DNA antibodies and a pro‐inflammatory response. The anti‐DNA antibodies can be produced by impaired clearance of apoptotic cells, which is the result of a hereditary deficiency of complements C1q, C3 and C4, which are involved in the recognition of phagocytosis by macrophages. Thus, it is likely that impaired clearance of apoptotic cells is able to provoke different types of immune dysfunction in cancer and autoimmune disease in which some are similar and others are critically different. This review discusses a comparison of immunological dysfunctions in cancer and autoimmune disease with the aim of exploring new insights beyond cancer immunosuppression in tumour immunity.

Purpose Cisplatin plus 5-fluorouracil has been globally accepted as a standard regimen for the treatment for advanced gastric cancer. However, cisplatin has several disadvantages, including renal toxicity and the need for admission. S-1 plus cisplatin has become a standard treatment for advanced gastric cancer in East Asia. This phase III study was designed to evaluate the potential benefits of adding docetaxel to S-1 without a platinum compound in patients with advanced gastric cancer.MethodsPatients were randomly assigned to receive docetaxel plus S-1 or S-1 alone. The docetaxel plus S-1 group received docetaxel on day 1 and oral S-1 on days 1–14 of a 21-day cycle. The S-1 alone group received oral S-1 on days 1–28 of a 42-day cycle. The primary end point was overall survival.ResultsOf the 639 patients enrolled, 635 were eligible for analysis. The median overall survival was 12.5 months in the docetaxel plus S-1 group and 10.8 months in the S-1 alone group (p = 0.032). The median progression-free survival was 5.3 months in the docetaxel plus S-1 group and 4.2 months in the S-1 alone group (p = 0.001). As for adverse events, neutropenia was more frequent in the docetaxel plus S-1 group, but remained manageable.ConclusionAs first-line treatment for advanced gastric cancer, docetaxel plus S-1 significantly improves median overall and progression-free survival as compared with S-1 alone. (ClinicalTrials.gov number: NCT00287768).

PurposeA retrospective study was performed to clarify the role of conversion therapy (surgery with a prospect of R0 resection performed in initially unresectable metastatic cancer that responded to the chemotherapy) in stage IV gastric cancer (GC).Patients and methodsWe treated 259 stage IV GC patients with systemic chemotherapy at Gifu and Hiroshima University Hospitals between 2001–2013. Of these, 84 patients who were subsequently treated by surgery were classified into four categories according to our previously published classification of stage IV GC, and short- and long-term outcomes were analyzed.ResultsSurgery was performed in 84 patients, of which 7 were performed following the neoadjuvant chemotherapy, whereas the other 77 that excluded neoadjuvant chemotherapy cases were considered the conversion therapy. The postoperative mortality and morbidity were comparable with those reported clinical trials. The MSTs of the patients with/without surgery for each category were 28.3/5.8 months for category 1, 30.5/11.0 months for category 2, 31.0/18.5 months for category 3 and 24.7/10.0 months for category 4. The MST of the R0 resected patients (41.3 months) was far better than that of the R1–2 resected patients (21.2 months). The MSTs of the patients with R0/R1–2 resection were 56.2/16.3 months for category 2, 33.3/29.6 months for category 3 and 40.7/17.8 months for category 4.ConclusionThere were long-term survivors who underwent conversion therapy for stage IV GC. Adequate selection of stage IV GC patients for conversion therapy may be an important role for the surgical oncologist in the new era.

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